But before getting off track comparing the n54 (which is a brilliant motor I don't care what you think) my original post was meant to compare the AMG motor with the M3 motor. It's amazing that BMW can compete on acceleration being down 2.2 litres.

There is much more to acceleration than just the engine. There is weight and gearing... both are hugely important. The M3 is competitive in acceleration with more powerful cars NOT because of the engine necessarily but because of the entire package of gearing, weight and engine. However, I would not argue the wonders of the S65 in the M3 as it is an awesome engine. The C63 can also produce far in excess of 500hp with not a lot of work.

I'm not dumping on the N54 but slap a turbo on almost any engine and it produces a lot of power. Tune the turbo for more boost and you get even more... that doesn't make an outstanding engine. The 335 isn't a fast car because it has an amazing engine with great gearing but rather because it has a very tunable turbo where cheap and easy gains are simple.

P.S. If you really wanted a fast car, you could have done better than an M3 with mods. By the time you put the mods on and the supercharger you are close to GT-R territory in price... make a few simple mods to that car and you have a complete monster. You seem to be very preoccupied with power and speed so I would have thought you would have picked a different starting platform (or maybe a 2013 GT500). Just saying.